function Food(ele){
  this.ele=ele
  this.len=20
  this.foodObj=null
  this.foodX=0
  this.foodY=0
}
Food.prototype.create=function(){
 let divObj=document.createElement('div')
 divObj.style.width=this.len+'px'
 divObj.style.height=this.len+'px'
 divObj.style.background='orange'
 divObj.style.position='absolute'
 this.foodObj=divObj
 this.ele.appendChild(divObj)
 this.move()
}
Food.prototype.move=function(){
    let foodXMaxNum=this.ele.clientWidth/this.len-1
    let foodYMaxNum=this.ele.clientHeight/this.len-1
    //坐标 随机个数
    // this.foodX=Math.floor(Math.random()*(foodXMaxNum+1))*this.len
    this.foodY=Math.floor(Math.random()*(foodYMaxNum-0+1)+0)*this.len
    this.foodX=Math.floor(Math.random()*(foodXMaxNum-0+1)+0)*this.len
    console.log(this.foodX);
    console.log(this.foodY);
    this.foodObj.style.left = this.foodX + 'px'
    this.foodObj.style.top = this.foodY + 'px'
}